Department of Physics, University of Alberta, 11322-89 Avenue, Edmonton, Alberta T6G 2G7, Canada.
Med Phys. 2010 May;37(5):2279-88. doi: 10.1118/1.3397455.
The details of a full simulation of an inline side-coupled 6 MV linear accelerator (linac) from the electron gun to the target are presented. Commissioning of the above simulation was performed by using the derived electron phase space at the target as an input into Monte Carlo studies of dose distributions within a water tank and matching the simulation results to measurement data. This work is motivated by linac-MR studies, where a validated full linac simulation is first required in order to perform future studies on linac performance in the presence of an external magnetic field.
An electron gun was initially designed and optimized with a 2D finite difference program using Child's law. The electron gun simulation served as an input to a 6 MV linac waveguide simulation, which consisted of a 3D finite element radio-frequency field solution within the waveguide and electron trajectories determined from particle dynamics modeling. The electron gun design was constrained to match the cathode potential and electron gun current of a Varian 600C, while the linac waveguide was optimized to match the measured target current. Commissioning of the full simulation was performed by matching the simulated Monte Carlo dose distributions in a water tank to measured distributions.
The full linac simulation matched all the electrical measurements taken from a Varian 600C and the commissioning process lead to excellent agreements in the dose profile measurements. Greater than 99% of all points met a 1%/1mm acceptance criterion for all field sizes analyzed, with the exception of the largest 40 x 40 cm2 field for which 98% of all points met the 1%/1mm acceptance criterion and the depth dose curves matched measurement to within 1% deeper than 1.5 cm depth. The optimized energy and spatial intensity distributions, as given by the commissioning process, were determined to be non-Gaussian in form for the inline side-coupled 6 MV linac simulated.
An integrated simulation of an inline side-coupled 6 MV linac has been completed and benchmarked matching all electrical and dosimetric measurements to high accuracy. The results showed non-Gaussian spatial intensity and energy distributions for the linac modeled.
呈现了对电子枪到靶的全内置侧耦合 6MV 直线加速器（linac）的完整模拟的详细信息。通过将靶处导出的电子相空间用作蒙特卡罗水罐内剂量分布研究的输入，并将模拟结果与测量数据匹配，对上述模拟进行了调试。这项工作的动机是 linac-MR 研究，为了在存在外部磁场的情况下对直线加速器的性能进行未来研究，首先需要对全直线加速器进行验证。
最初使用二维有限差分程序和 Child 定律设计和优化电子枪。电子枪模拟作为 6MV 直线加速器波导模拟的输入，该模拟包括波导内的三维有限元射频场解和由粒子动力学建模确定的电子轨迹。电子枪的设计受到约束，以匹配瓦里安 600C 的阴极电位和电子枪电流，而直线加速器波导则进行了优化，以匹配测量到的靶电流。通过将模拟的蒙特卡罗水罐中的剂量分布与测量的分布相匹配，完成了全模拟的调试。
全直线加速器模拟匹配了从瓦里安 600C 获得的所有电气测量值，调试过程导致剂量分布测量结果非常吻合。除了最大的 40x40cm2 场之外，所有场的 99%以上的点都符合所有分析的场大小的 1%/1mm 接受标准，对于 98%的所有点符合 1%/1mm 接受标准且深度剂量曲线与测量值相差 1%以内的最大 40x40cm2 场除外。调试过程确定，所模拟的内置侧耦合 6MV 直线加速器的优化能量和空间强度分布在形式上是非高斯的。
已经完成了全内置侧耦合 6MV 直线加速器的集成模拟，并通过高精度匹配所有电气和剂量测量来进行基准测试。结果表明，所模拟的直线加速器的空间强度和能量分布是非高斯的。
